The invention relates to an antifriction mounting including a bearing with a rotation speed indicator and relates to a seal for the bearing and for part of the indicator.
There is a need to provide many types of antifriction mountings with a device for detecting rotational speed. Thus, the prior art discloses fitting a wheel bearing of a motor vehicle with a rotational speed detector, for example, to derive the speed from the signals obtained and to use the speed information to control an antilock system. For this purpose, a pulse generator is fastened to a rotating bearing part, and a stationary rotational speed sensor is arranged in the immediate vicinity of the pulse generator so that it can detect the position or movement of the pulse generator part.
An antifriction bearing having a pulse generator disk integrated into the seal at one axial side of the bearing is disclosed in DE 37 35 070 A1. This pulse generator disk has the form of a perforated plate. The position of the perforated plate can be detected, for example, by a suitable arrangement of a permanent magnet and a HALL sensor. The disadvantage of this principle is that damage occurs to the perforated plate pulse generator, which is arranged outside on the bearing.
EP-A 0 607 719 A1 discloses integrating an elastomer pulse generator, magnetized in a multipolar fashion, into the rotating bearing seal such that it is situated on the outside as a centrifugal disk. The magnetic multipolar generator has the advantage that the sensor head can be kept small. However, this arrangement has the disadvantage that the multipole magnet is open to the outside, enabling magnetic particles to be attracted from the environment. These particles accumulate on the pulse generator surface and lead to short circuiting of the magnets. They can cause false signals, reaching as far as functional failure of the rotational speed measuring system.